What antenna should I use?

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Hawkeye

What antenna should I use?

#262392

Post by Hawkeye »

I had a Realistic DX-150 shortwave radio awhile back. Long story short, I sold it. Now I miss it and plan on getting another soon. I still have the dipole I used with the other reciever that I plan to use with the next one. This dipole worked well with this reciever.
The Realistic DX-150 covers 535 to 30000 kHz.
Is the dipole I have a good antenna for general use? Or will I need to buy a more perminate mounted aluminum antenna for better reception throughout the range?
One more question about the dipole.
When last in use I draped it over my window sill for reception in the house. I`m considering tacking it under my 2nd floor eave. If I buy a 20 foot extention coax to get it to the eave, will it change how it performs?
'Doc

Re: What antenna should I use?

#262410

Post by 'Doc »

Will extending the feed line make any difference in what you hear? Maybe, but probably not a great deal either way. Receiving antennas are different than transmitting antennas. The don't need to be as 'exact' in any particular way. The two things that would result in better performance is height and length. The range in length would be something like 8 feet (30 Mhz) to 400 feet (500 Khz). [Those lengths are for half of a dipole's length, or 1/4 wave lengths.] The lower in frequency the longer the antenna. Lengths for lower frequencies tend to work just fine on higher frequencies, so in general, the longer the better.
If the eaves of your house are higher than where that dipole was before, you should see/hear some improvement in reception. Maybe not a huge difference, but some. Lay the thing on top of the house and there should be even an itty-bit more improvement.
All kinds of ways to hear better, just depends on how much trouble you want to go to.
Have fun.
- 'Doc
Hawkeye

Re: What antenna should I use?

#266199

Post by Hawkeye »

OK, one more question please.
The current dipole i have for a shortwave radio has approx 7 feet of feedline to the "T" in the dipole and the dipole end to end is only about 4 foot long.
Can I do better by getting a longer dipole or just a longer wire?
Currently this one just draped along my curtain in the closest window. I want to put up something more permanant by placing a new dipole or wire (If you all feel this would work better) outside under my second floor eves. Sure this would work better because the antenna is outside, but forget this variable for the moment. Would a longer dipole or wire do better than my current small dipole?
Thanks All
'Doc

Re: What antenna should I use?

#266249

Post by 'Doc »

A longer antenna would mean better reception at lower frequencies, it would be closer to 'resonance' than a shorter antenna. That dipole you're using now isn't even close to 'right' for any frequency under 30 Mhz (30000 Khz), so a longer one would have to do better.
I'm sort of cheap so buying an antenna is one of the last things I'll ever do, if I can make one. Antennas don't have to be made of any certain thing, it just has to be conductive. That means that in most cases that plain old every-day wire will work just dandy, especially for a receive only antenna. The size of that wire isn't important except it should be strong enough to hold up it's own weight without breaking. Doesn't matter if it's insulated or not. Orientation can be important. That means that to receive a vertically polarized signal, a vertical antenna works better than a horizontally polarized one will. A radio signal get's it's polarization form the kind of antenna it's transmitted from, vertical/horizontal. Most commercial broadcasting is vertically polarized. Most things above 30 Mhz is probably horizontally polarized (TV for instance). Non-commercial broadcasting/transmitting can be either (CB, ham, whatever).
So, keeping all that in mind, after some judicious thought, you will only be wrong maybe half the time, sort of.
There's a trick you might try. Find enough wire of some size that it won't break, tie a rock on the end of it and throw it over your roof. Hook the other end of it to your radio. See if it improves anything (it will). Or better yet, make that a string going over the house, tie a wire on the end of it so you can pull more wire up and over. See how antenna length makes things better/worse. Got a particular part of the radio spectrum you like listening to? Adjust wire length for best reception on that part of the spectrum. Wanna try a horizontally polarized antenna? Run that wire horizontally under your eaves, that's one way of doing it.
If you don't get the antenna tangled in a power line, I seriously doubt that any antenna will ever harm that receiver. So, play around as much as you want (or can get by with?). The only warning I think you should really pay attention to is that if you break anything with that rock you used to throw whatever over the house, I did NOT tell you to do that! You are on your own there Bud!
Have fun.
- 'Doc


(That rock, technically called a 'chunker', is only as good as your throwing arm. Potato-guns, mortars, cannons, are the best chunkers in the world! The line launchers used on maritime vessels are only a variation of a potato-gun.)
Hawkeye

Re: What antenna should I use?

#266275

Post by Hawkeye »

[quote="'Doc"]
There's a trick you might try. Find enough wire of some size that it won't break, tie a rock on the end of it and throw it over your roof. Hook the other end of it to your radio. See if it improves anything (it will). Or better yet, make that a string going over the house, tie a wire on the end of it so you can pull more wire up and over. See how antenna length makes things better/worse. Got a particular part of the radio spectrum you like listening to? Adjust wire length for best reception on that part of the spectrum. Wanna try a horizontally polarized antenna? Run that wire horizontally under your eaves, that's one way of doing it.
If you don't get the antenna tangled in a power line, I seriously doubt that any antenna will ever harm that receiver. So, play around as much as you want (or can get by with?). quote]

This sounds like my best bet here. Would speaker wire do ok? I`m only wondering because its insulated and very flexable.
If another wire would be better suited, do tell.
'Doc

Re: What antenna should I use?

#266295

Post by 'Doc »

The best wire to use is whatever you happen to have enough of that is strong enough. Typical speaker wire ought'a work just fine. If it's 'paired' as in 'zip-cord', pull it into two pieces, you got twice as much! Make good splices, they are usually the weakest points. Lots of 'practical' stuff with this sort of thing, very little magic at all.
- 'Doc


(The only 'magic' with any of this stuff is when it works right the first time! Sort of.)
Hawkeye

Re: What antenna should I use?

#266856

Post by Hawkeye »

"Typical Speaker Wire" you say Doc.
What gauge is typical speaker wire?
I was looking at my local Wal-Mart. They had 14 gauge, 16 gauge and 24 gauge. Of course the 24 gauge had double the length the 14 gauge did for less than half the price. And I can even split it for twice the length.
'Doc

Re: What antenna should I use?

#266863

Post by 'Doc »

Hawkeye,
Once upon a time, 'speaker' wire used to be the cheapest wire you could find. Because of that, saying that even 'speaker wire' could be used for something wasn't exactly saying anything special at all, in fact, just the opposite. Today, it's meant the same way, except that some 'speaker wire' can be pretty dang big and expensive. So instead, just think of antenna wire as only having to be an electrical conductor large enough, or strong enough to hold up it's own weight and whatever happens to be attached to it. That #24 wire is approaching the point where it's strength is going to be sort of "iffy", or a bit 'delicate', you know? Not exactly the strongest stuff in the world. Electrically it would work just fine, but watch out about snapping in two.
The best antenna wire you can get is the cheapest and strong enough to take the handling of getting it strung up, and just hanging around, sort of. Doesn't make any difference what it is or is called, if it's insulated ot not. Naturally, it helps if it's fairly easy to put an connector on, or attach to a radio's antenna terminals in some way. Electric fence wire is probably the cheapest stuff around. Comes in 1/4 mile spools. It's also not the easiest stuff to use. It's stiff, will 'swarm' on you if you're not careful, kinks like crazy, and is galvanized which makes soldering sort of difficult at times. If you don't mind handling the aggravating stuff, you can get a lot of antenna(s) out of a 1/4 mile of wire! And it isn't exactly 'pretty'. Use whatever you have or can find that doesn't 'bite' your wallet too much and that you can deal with it's 'draw-backs'.
Pink insulated wire has got to be the 'best' you can use! Nobody want's it, so it's cheap. Electrons gather around it asking each other, "What the hell izat?", and receivers can grab them easier. Also 'best' for transmitting antennas because when an electron looks back and sees what it just came from, it want's to get as far from it as possible! It doesn't have to make sense, if it works, right?
- 'Doc
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